The project aims at the development of silicon doped tricalcium phosphate (Si-α-
TCP) and at the preparation of the corresponding cements for bone tissue
engineering applications.
There are two principal objectives into this project:
First, to optimize the parameters of a wet milling method in order to obtain Si-α-
TCP with high purity.
Then, to use the Si-α-TCP produced as the main reactant to prepare calcium
phosphate cements doped with silicon. The formation of Si-CDHA as final phase is
evaluated.
The Si-α-TCP is prepared by milling hydroxyapatite and silicon oxide with water,
followed by a heat treatment. In order to maximize the preparation of Si-α-TCP
phase, some conditions have to be optimized: the reactants ratio, the milling
process and the thermal treatment. The study carried out shows that a single
stabilized α-TCP phase is produced when hydroxyapatite and silicon oxide, are
milled according to a 0.48 SiO2/HA molar ratio, and heat treated at 1250°C
during 2 hours. The fact that silicon stabilizes the α-phase is revealed by the
obtaining of this phase while no quench was performed.
A grinding process is carried out with the Si-α-TCP prepared to lead to the powder
phase for cements. Finally, cement is prepared by mixing a calcium phosphate
powder with water. The liquid to powder ratio is also adjusted in order to obtain
cements with appropriate properties to be used for bone regeneration. Cement
samples are stored under body simulated conditions and are evaluated at different
time points.
The Si-α-TCP powder reacted with water with similar reaction kinetics than α-TCP
powder free of silicon. Furthermore, cements prepared from Si-α-TCP powder have
the same physic-chemical properties than cements prepared from α-TCP powder
free of silicon. The studies performed were not conclusive on the silicon
incorporation into the CDHA, and future studies will be required in order to
evaluate this incorporation.